Help a girl with her electricity please?

[Skean Dhude]

You can wire then up that way now. Then when you go and redecorate you can bury the cables in the walls to hide them.

Remember that the lower the voltage the more voltage gets dropped. So site your batteries centrally and don't have runs that are long especially for the power greedy components.

I'm moving my stuff around. Power greedy stuff in garage with the batteries and power panels. The house is mainly 12V LEDs as well as comms chargers.

[NorthernRaider]

(11 June 2013, 10:08)Skean Dhude Wrote: You can wire then up that way now. Then when you go and redecorate you can bury the cables in the walls to hide them.

Remember that the lower the voltage the more voltage gets dropped. So site your batteries centrally and don't have runs that are long especially for the power greedy components.

I'm moving my stuff around. Power greedy stuff in garage with the batteries and power panels. The house is mainly 12V LEDs as well as comms chargers.

Bloody good common sense info there SD Planning make perfect.

[Skvez]

For the same POWER of unit running at 12V (rather than 230V) it will draw 19 times more current and so will need cables much thicker cables (not exactly 19 times as thick but think MUCH thicker). This is the main reason why we use 'high' Voltage.
When we discuss LED lights this doesn't really matter but once you get into discussing 'white goods' it does matter.

Then you need to consider Voltage drop.
A 2.4V Voltage drop across a cable when you are feeding in 230V (and getting out 227.6V) is tolerable.
Doing the same at 12V in and 9.6V out is not tolerable so you need to uprate the cable again!

Low Voltage means very heavy duty (expensive) cable.

[Timelord]

If the distance of cable is short, then voltage drop is not as bad. On transmission networks - High voltage is 11000volts up. Medium voltage is 415v up to high and below that is not on the transmission network as it is by now in the consumer premises. High voltage is used on national transmission and local transmission networks due to the voltage drop issues and in that it is far more efficient to transmit electricity along long wires at these voltages. Step down transformers are used to drop the voltage successively until it reaches the customers premises. 230Volts is used in domestic premises as it is still high enough to overcome voltage drops efficiently - as Skvez says. Running "white goods" type equipment is not very efficient on a 12volt system. If you are having design problems, you could try two further options.
1) rig the wiring system up as a 24volt circuit from a multiple battery, with a voltage drop unit to 12 volts at the connection of each item of 12volt equipment. That will help with the voltage drop problem to some degree.
2) to avoid purchasing expensive thicker cable, you could double the number of cables, ie. run two cables instead of one to each unit. This is not as neat but will provide more cross sectional area of wire for the current to pass along. Although doubling the cable runs does on the face of it increase the cost of purchasing the wiring, thinner cabling can be sourced more easily at cheaper prices and bigger cable reels are pro rata cheaper than smaller cable reels to buy. Try non ferrous scrap metal yards. They often have whole or substantial rolls left over from customers trade jobs - going very cheap or ebay or gumtree etc. Regards, TL

[uks]

Voltage drop what would be the longest length you could run before you noticed a drop?. Are we talking centimeters or metres.

[NorthernRaider]

IIRC AC current is the choice of the power companies primarily because it doesnt lose so much energy in long transmission lines. But DC is more efficient overall but its loses to much energy after a few hundred meters and switches for DC have to be different to AC ones as DC power can weld ordinary switches open or closed. The guys who originally started generating power way back when soon realised that though DC was the better system they would have to put a power plant at the end of each street just to deal with the drop.

A household domestic DC system should be attainable fairly easiily.

[uks]

Sorry should have stated 12 volt.

[NorthernRaider]

UKS I have heard of people using 24VDC in very large industrial units which they then drop to 12vdc for use ??

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This thread on eco ideas may help http://challenge.ecomagination.com/home/...lt-systems-

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And this
http://www.treehugger.com/sustainable-pr...lt-dc.html

Here is a good simple article

http://www.selfsufficientish.com/12v.htm

and this is slightly more technical

http://www.dreamgreenhouse.com/designs/12v/

[Alterego]

(29 May 2013, 20:03)ErikEst Wrote: since most of the domestic appliances are made for 230V AC so it is more economical to use 12V-230V inverter.
with your 1000W inverter you can power light bulbs, refrigerator, radio, tv, computer as long as total consuming power is not exceeding 1000W. one classic light bulb has 60W power, modern LED bulbs are 7 to 14W, refrigerator has 300 (bigger ones 600W) when its compressor is on, modern tv has about 100W. so you can calculate how big inverter you need or how much light or appliances you can switch on.

batteries, on every 12V battery you can see its capacity shown in AMP per hour (A/h). usual family car battery has more or less 60A/h capacity. means that you can get 60AMPs of current for the 1 hour or 6AMPs for 10 hours.
now we know that one Watt equals one Volt times one Ampere (1W=1V x 1A).
so for running your 1000W inverter on full power you need at least same power coming from your battery. 1000W divided by 12V is 83,33AMPs. this means your battery is only good for about 45 minutes. more batteries you have connected in parallel the more battery capacity you have the longer you can use your lights or refrigerator.
this means you have to cut on electric consumption and use as many solar batteries as you can afford to charge your batteries.

thats not stirctly true....the wattage stated on an invertor is the PEAK power NOT the Actual or SERVICE P.....

why? because they are not 100% efficient

the remaining 25% is shown up as heat..

to be safe i would aim for 75% of the wattage stated..eg 750 watts..

to assume the available power from a 1000 watt invertor is 1000 watts will lead you to the invertor shop in a short space of time...


Alterego